You will need to force your Apple device to restart if it continues to freeze and lock up after you have shut it down and turned it back on. The hard reset of an Apple Watch is also called this.
You can do this in a few seconds using this simple method. Please keep in mind that this will not affect the data on your apple watch. The Apple watch device is simply restarted. Read the full blog here: https://www.soldrit.com/blog/how-to-force-restart-or-hard-reset-apple-watch/